Abstract : The active flow control is currently one the major issues in aerodynamics for reducing the drag, increasing the lift and controling instabilities. The aim of this study was to develop plasma actuators. The physical properties and their effects on subsonic flows were characterized. Two configurations were used: DC surface corona discharge and AC sine dielectric barrier discharge (DBD). Electrical and optical measurements showed that these plasmas consisted of several high frequency micro-discharges. The "ionic wind" induced by these actuators was non-stationary, quite slow (a few m/s) and strongly depended on geometrical and electrical configurations. This mechanical property was used for modifying the boundary layer evolving on a flat plate and on airfoils. A succession of DBD enabled to pre-tripped the boundary layer laminar-to-turbulent transition. Flow seperations on airfoil leading edge have been delayed or deleted by plasma actuators. Finally, new kinds of actuators were developped: a pulsed DBD and plasma jets generated perpendicularly to the wall.